BOTTOM LINE UP FRONT — Headlines from North Korea rarely bring good news in the realm of global security, but this week’s bulletin from Pyongyang was particularly concerning to close watchers of the country: North Korea is well on its way to building a nuclear-powered submarine.
The country’s state media released photos of what it called a “nuclear-powered strategic guided missile submarine” that was under construction, and showed North Korean leader Kim Jong Un inspecting shipyards where it was being built. The Associated Press quoted a South Korean expert estimating that that the 6,000–7,000-ton submarine could carry 10 nuclear-capable missiles, significantly enhancing the North’s ability to launch underwater attacks.
In 2021, Kim laid out a list of major weapons he wanted in the country’s arsenal – a list that included ICBMs, hypersonic weapons, and spy satellites, as well as a nuclear-powered submarine.
Various experts – including those at The Cipher Brief – believe North Korea obtained the resources and technology to build the submarine through its recent collaboration with Russia; last year, North Korea sent more than 10,000 troops to help Russia defend territory in its Kursk region against a Ukrainian incursion. By many accounts, large numbers of those troops have been killed or wounded, and North Korean has sent even more forces to Russia. The quid pro quo was always understood to involve Russian military and technological assistance to North Korea.
The Cipher Brief spoke about the submarine and its implications with three Cipher Brief experts: Admiral Mike Studeman, former Commander of the Office of Naval Intelligence, Admiral James Stavridis, former Supreme Allied Commander for NATO, and Ambassador Joseph DeTrani, a former Director of East Asia Operations for the CIA.
The conversations have been edited for length and clarity.
THE CONTEXT
- In January 2021, at the 8th Congress of the Workers’ Party of Korea, North Korean leader Kim Jong Un announced a goal of developing a nuclear-powered submarine as part of a five-year weapons development plan. Kim said the submarines would strengthen North Korea’s nuclear deterrent.
- North Korea has been developing submarine-launched ballistic missile (SLBM) systems for years. The country has also conducted several SLBM tests since 2015.
- In September 2023, North Korean leader Kim Jong Un met with Russian President Vladimir Putin at the Vostochny Cosmodrome in the Amur region of Russia's Far East. Kim offered North Korea’s support for Russia, and the two discussed Russian support for North Korean development of satellite and other technologies. In June 2024, Putin visited Pyongyang, where he signed a comprehensive strategic partnership treaty with Kim, pledging to counter “aggression” against either of their countries.
- North Korea has deployed 10,000-12,000 soldiers to support Russian troops in Russia’s western Kursk region in countering Ukrainian troops who launched an incursion there in August 2024. Experts say Kim is likely getting military development support in exchange for the troop contribution.
THE EXPERTS
RADM Studeman: [To understand the threat to the U.S.], you start looking at the estimated ranges of some of the different submarine-launch ballistic missiles (SLBM) that have been tested by North Korea, or produced, and then looking at an arc. Some of the tests were fairly short-range, early SLBMs on the range of 500, 600 kilometers max, which would be inside the Sea of Japan in terms of range.
But the later ones that the North Koreans have developed – or we think we have seen them develop – start to get up into the thousands of kilometers range. One version may be between 2,000 and 2,500 kilometers, and then their more advanced one, the Pukhong Song 5, may be up to 3000 kilometers. If we were to take a look at what that means, if you consider where North Korea is, they would station these submarines on their east coast because there's deep water. And if you extend 3,000 kilometers from around there, the operating area of this new nuclear-powered submarine with nuclear-tipped missiles, you can actually range all the way down to Guam. You still can't reach into the main parts of Alaska; you'd have to come outside the first island chain and be operating up (in the northern Pacific) to do so.
Most people would probably conclude, based on North Korea's priorities, which are targeting South Korea and Japan and having a capability to hold those targets at risk, that we should first think about what their capability could be, and the contingency that involves those two countries. So yes, the United States is at greater risk if this nuclear-tipped submarine begins to deploy in those areas with that long-range missile system, the longest they would have from their submarines. But there's also the case to be made that they really want to be able to maneuver around the Theater High Altitude Air defense capabilities, the THAAD batteries, which are deployed in South Korea. They would want to get outside of their scan, their radar view. And if all your threats come from land-based ballistic missiles that are coming from the North, it actually makes it easier for our THAAD and Aegis BMD and Patriots to be able to know the vector that is coming. If you're North Korea and you want to get guaranteed penetration, then you need to go from a different aspect. And this is what the submarine may give them, an ability to essentially come in from the side and be able to complicate air defenses in a South Korea contingency.
That would certainly change the equation. It would mean threats to South Korea, threats to Japan, threats to the United States, all of them kind of bundled up. But we have to see them actually begin to do the sea trials, the training, the operations. We're talking at least two, three, maybe more years away before we might get a sense for it. And it should be noted that if you really want to have a full-fledged, guaranteed second-strike at-sea capability, you need at least three of those kinds of submarines – probably even more, four or five, given the state of maintenance and how you need to rotate deployments. So we're many years, if not closer to a decade away, to being able to see something of that ilk, with a constant presence in an area that would reliably threaten the United States. But if they're moving toward that capability, we need to track it very closely.
I think the Chinese would be worried. I think a limited view would be one where you'd say, Well, if they created it, then it would maybe consume more energy by the United States and others to put ISR (intelligence, surveillance and reconnaissance) on it, and that that’s a good thing for China. And maybe North Korea might do something with its submarines to distract us during a contingency, say, over Taiwan. I just don't think that level of planning and collusion exists, that the relationship is at that level. I think the relationship has frayed over the years. There isn't the warmth. I think there's very antiseptic relations between North Korea and China.
Admiral Stavridis: It’s an example of payback from Russia for the 12,000 [North Korean] foot soldiers – and there’s plenty more where those came from – that are being thrown at the front lines [in Russia’s Kursk region] on behalf of Russian President Vladimir Putin. What has Putin given back to North Korea? He’s given intelligence, he’s given nuclear technology for weapons, and now it appears he’s going to help advise the North Koreans on building a nuclear-powered submarine. It’s unclear at this moment whether the submarine will also have ballistic missiles. Certainly it will have cruise missiles of some kind.
As we all know, nuclear submarines are the apex predators of the ocean. One of those in the hands of [North Korean leader] Kim Jong Un ought to give us all pause.
If Kim were able to carry out an ongoing build program, and he was able to put to sea four to six nuclear-powered attack boats with decent sensor systems, hypothetically – if he could do that over the next decade, that would put him in a very strong position in undersea warfare. For example, this could prevent us from attacking Chinese forces blockading Taiwan. Our ace card is our nuclear-powered attack boats. Could Kim counter those?
And then secondly, and even more worrisome, if this nuclear-powered submarine had at a minimum cruise missiles, those can be driven across the Pacific, parked outside of Pearl Harbor, outside of Los Angeles, outside of Washington State. We would see his ballistic missiles coming. But a submarine, nuclear-powered, can stay underwater indefinitely, essentially. If it then adds cruise missiles to the repertoire, it holds major American cities and military targets at risk. That ought to worry us a lot.
For China, North Korea obtaining nuclear attack submarines is exactly like the United States having Australia obtain nuclear-powered submarines, which they’re doing right now. This is part of the AUKUS alliance and program – Australia, the U.S., and the United Kingdom. If both Russia and China are providing submarine technology to Kim Jong Un, that becomes the Asian version on the authoritarian side of AUKUS.
By the way, I am a proponent of bringing Japan into that AUKUS agreement. There are pros and cons to doing that, and the Japanese are still not lit up about nuclear power, given their own experience at Hiroshima and Nagasaki. I think they’ll get much more interested if Kim starts to build nuclear submarines. It’s not just about China and Taiwan, it’s also about Japan. That could be the catalyst to bring Japan into AUKUS, which would be a very good thing.
Ambassador DeTrani: I'm not surprised, but I'm very concerned. Starting in 2021, Kim Jong Un made it very clear he was going to be working on hypersonics, cruise missiles, and nuclear submarines. And then you saw his visit to Vladivostok, the base of the Russian Pacific fleet. It's pretty clear that Kim Jong Un was very serious in 2021, and he's very serious now.
It gives them a significant reach, and capabilities that, relying on their ballistic missile systems, they do not have. But with a submarine, certainly a nuclear-powered submarine capable of launching up to eight or 10 ballistic missiles, that's very significant.
And there's no doubt in mind where they're getting this technology from. Again, his visit to Vladivostok and the Russian Pacific Fleet, these were strong indicators of where North Korea was going. We have seen Putin's willingness to provide this assistance to Kim Jong-un, to give him these capabilities. I believe he got some of this technology, some of the expertise from the Russian Federation. It’s a quid pro quo [for North Korean military aid in the Ukraine war]. Russia is now helping them.
One of the major diplomatic blunders, the errors we made was not seeing Kim Jong Un moving closer to Putin and the Russian Federation. Whether it's diplomatic or intelligence-wise, this is significant. I've written in the past it was symbolic, that what the North Koreans were doing with their 10-12,000 troops in Russia, in the Kursk region was symbolic. I stand corrected on that. I now think this is very strategic between these two countries.
This is all unsettling for China. I think what Kim Jong-un has done with Vladimir Putin and the Russian Federation, the mutual defense treaty and so forth, this is all unsettling to China. China knows they have a lot of leverage over North Korea: 90% of the trade, the crude oil, petroleum products from China, and so forth – North Korea is now getting a lot of that now from Russia. They're getting the food aid, they're getting the crude oil, they're getting energy assistance, and they're even getting ballistic missile assistance and satellite assistance. So this is very unsettling for China. And I think in some ways Xi Jinping and his team have to look back and say, maybe we should have done more during the past four years to get North Korea to sit down with the Biden administration and talk about some of the issues. Because I think now China is not only concerned, but they are also concerned now that we have a new president and there's a new dynamic. And there's a lot going on in North Korea and in the United States.
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